Method and furnace for bending glass panels

Abstract

The invention relates to a method and furnace for binding glass panels. Preheating compartments ( 3 ) upstream of a binding compartment are used for heating a glass panel by hot-air injection applied to the top and bottom sides of a glass panel. The air employed in hot-air injection is circulated through heating resistances ( 15, 16 ). Outputs of the heating resistances ( 15, 16 ) can be adjusted for individually adjusting the temperatures of air injected to the top and bottom sides of a glass panel. The glass is heated to the proximity of a bending temperature exclusively or mainly by means of convection.

1 . A method for bending glass panels, said method comprising supporting a glass panel on a bending mould, conveying the glass panel as well as the bending mould on a carriage from a preheating compartment to another and raising the glass temperature in successive preheating compartments to what is almost a bending temperature, carrying the glass panel as well as the bending mould into a bending compartment for bending the glass panel therein, followed by cooling the bent glass panel, wherein in the preheating compartments the glass is heated by hot-air injection applied to the top and bottom sides of a glass panel, and the air used in hot air injection is circulated through heating elements provided with heating resistances whereby the air is heated to a desired temperature.  
   
   
       2 . A method as set forth in  claim 1 , wherein the air to be injected to the top side of a glass panel is circulated through a first heating element and the air to be injected to the bottom side through a second heating element, and the first and second heating elements have their outputs adjusted individually.  
   
   
       3 . A method as set forth in  claim 1 , wherein temperatures of the air injected to the top and bottom sides of a glass panel are measured separately and the heating elements have their outputs adjusted on the basis of measured results.  
   
   
       4 . A method as set forth in  claim 1 , wherein glass panels are allowed to cool in cooling compartments beneath the preheating compartments, wherein the mould carriages are conveyed non-stop past and under two or more preheating compartments equipped with hot-air injection.  
   
   
       5 . A furnace for bending glass panels, comprising a number of bending moulds and mould-conveying carriages whose end walls compartmentize the furnace for successive preheating compartments, a bending compartment and cooling compartments preferably below the preheating compartments and possible pre-bending compartments, wherein the preheating compartments are associated with air circulation channels, heating elements and fans therein for circulating the air aspirated from the preheating compartments through the heating elements and for injecting the heated air to the opposite sides of a glass panel in the preheating compartment.  
   
   
       6 . A furnace as set forth in  claim 5 , wherein the channel systems applying heating air to the top and bottom sides of a glass panel are provided with individually adjustable heating elements provided with heating resistances, hence the temperatures of heating air applied to the top and bottom sides of a glass panel being individually adjustable.  
   
   
       7 . A furnace as set forth in  claim 5 , wherein the air circulation channels are located in the preheating compartments on the opposite sides of a glass panel and provided with orifices or nozzles for distributing hot-air jets in a substantially consistent manner over the entire area of a glass panel and for directing the same against the top and bottom sides of a glass panel.